HIV is known to replicate primarily in activated CD4+ T cells. In addition, HIV can remain silent in unactivated T cells - what is referred to as the latent reservoir. Because current anti-retroviral agents only target actively replicating virus, the existance of a latent reservoir is the primary reason why current strategies do not eliminate HIV from people. This study seeks to define the subsets of CD4+ T cells in patients that contain HIV - in both active and latent forms - as a basis to develop strategies to eliminate HIV from the body. In addition, the project seeks to study ways in which to limit SHIV replication in non-human primates as a model system for studying HIV replication in humans.